1. Field of the Invention
The present invention relates to a reciprocating compressor, and in particular to a driving apparatus of a motor which is capable of driving a motor of a reciprocating compressor stably and efficiently without using a microcomputer.
2. Description of the Prior Art
In general, a compressor is for compressing a refrigerant circulating a cooling apparatus such as an air conditioner and a refrigerator so as to be in a high temperature-high pressure state.
Compressors can be divided into several types. For example, there is a reciprocating compressor, a rotary type compressor, a BLDC (brushless direct current) type compressor, an inverter type compressor and a variable reciprocating compressor having a variable rotational speed. Herein, because the reciprocating compressor can vary a piston stroke according to a rotational force of a motor, it is possible to control cooling capacity according to a user's intention. A driving apparatus for driving the reciprocating compressor will be described with reference to accompanying FIG. 1.
FIG. 1 illustrates a driving apparatus of a reciprocating compressor in accordance with the conventional art.
FIG. 2 is a wave diagram illustrating a piston stroke of the reciprocating compressor in FIG. 1.
As depicted in FIG. 1, the driving apparatus of the reciprocating compressor in accordance with the conventional art includes a capacitor C for applying a power voltage (for example, AC) to a motor 10. Herein, the capacitor C performs a function for maintaining varying piston stroke uniformly as a set piston stroke when an operational load of the reciprocating compressor is varied.
In the conventional driving apparatus of the reciprocating compressor, when a power voltage is supplied to the motor 10 through the capacitor C, impedance in the motor 10 is reduced as same as capacitive reactance of the capacitor C due to electric resonance characteristics. In addition, a counter electromotive force does not exist in the motor 10 in the initial operation state of the reciprocating compressor.
Accordingly, as depicted in FIG. 2, because the impedance is reduced in the counter electromotive force non-existence state, the power voltage supplied to the motor 10 is increased, an excessive stroke in which a piston (not shown) may collide against other construction parts installed at the top or bottom portion of a cylinder of the reciprocating compressor may occur.
In the meantime, in the initial operation state of the reciprocating compressor, when the power voltage is supplied to the motor 10 through the capacitor C, in order to prevent an excessive piston stroke, the power voltage supplied to the motor 10 is controlled by using a microcomputer. It will be described with reference to accompanying FIG. 3.
FIG. 3 illustrates another example of a driving apparatus of a reciprocating compressor in accordance with the conventional art.
FIG. 4 is a wave diagram illustrating a piston stroke of the reciprocating compressor in FIG. 3.
As depicted in FIG. 3, the driving apparatus of the reciprocating compressor in accordance with the conventional art includes a microcomputer 11 for adjusting a power voltage as a certain voltage value and outputting the adjusted voltage in the initial operation of the reciprocating compressor; a capacitor C for applying the power voltage adjusted by the microcomputer 11 to a motor 10; and the motor 10 for varying a piston stroke of the compressor by being operated according to the power voltage applied through the capacitor C.
First, the microcomputer 11 adjusts the power voltage for operating the reciprocating compressor as a voltage value such that an excessive stroke is avoided, and outputs the adjusted voltage to the motor 10. In more detail, as depicted in FIG. 4, the motor 10 maintains a stable piston stroke in the operation by the power voltage applied through the capacitor C.
However, when the reciprocating compressor is operated, because the power voltage supplied to the motor is controlled by the microcomputer, production cost of the reciprocating compressor may be increased due to the presence of the microcomputer.